1. Field of the Invention
The present invention generally relates to sewing machines of a type which sews an elongated sewn material, such as a tape or cord, to an object of sewing (typically, fabric) through lock stitching. More particularly, the present invention relates to an apparatus and method for cutting an elongated sewn material, for example, at the end of sewing.
2. Description of the Related Art
Conventionally, there have been known sewing machines of a type which includes a vertically driven needle bar, a sewing needle fixed to a lower end portion of the needle bar, a rotary member mounted concentrically with the needle bar and freely rotatable about the axis, and a guide fixed to the rotary member, for guiding an elongated sewn material (e.g., string-shaped embroidering member, such as a tape or cord) to a sewing position of the sewing needle. The sewing machines of the type operate to sew the string material to a fabric through lock stitching, by the rotation of the rotary member being appropriately controlled in accordance with a moving direction of a fabric based on embroidery data and by the orientation of the guide being appropriately varied to optimize the direction in which the string material is guided to the sewing position of the sewing needle. One example of such sewing machines is known from Japanese Patent Application Laid-open Publication (Kokai) No. H04-163361. The No. H04-163361 publication discloses a cutting apparatus which cuts a string material in a sewing machine of the above-mentioned type. Brief description will now be given of the cutting apparatus disclosed in the No. H04-163361 publication. This cutting apparatus is comprised of a support member which is moved to a retracted position which does not interfere with sewing operation and an advanced position near the sewing position of the sewing needle, and a hook member which is provided on the support member and movable forward and backward so as to hook the string material thereon. The support member always lies at the retracted position during sewing, and when it is necessary to cut the string material having been used for sewing, for example, at the end of sewing, the support member can be moved to the advanced position. When the support member lies at the advanced position, the hook member is moved forward and backward to hook thereon the string material at the sewing position and draw the string material to the support member, and then the string material is cut. In this case, an upper thread as well as the string material is cut at the same time.
In the conventionally-known cutting apparatuses like the one as disclosed in the No. H04-163361 publication, a drive source for moving the support member to the retracted position and the advanced position, and a drive source for moving the hook member forward and backward are separately provided as individual dedicated drive sources. However, there has been the problem that, since such a cutting apparatus driven by a plurality of drive sources is expensive and large in size, the sewing machine is also expensive and making the sewing machine compact is difficult. There have also been known cutting apparatuses of a type which is provided with the third drive source for driving a cutting blade which actually cuts a string material, but the cutting apparatuses of this type would suffer from the inconveniences that the cost and size are further increased.
Further, in sewing a string material (elongated sewn material), it is necessary to pull a certain amount of the string material out of the guide and to leave a certain amount of the upper thread at a tip of the sewing needle so that the string material can be reliably sewn onto a fabric at the beginning of sewing. However, in the conventionally-known cutting apparatuses like the one disclosed in the No. H04-163361 publication, after the support member is moved from the retracted position to the advanced position near the sewing position of the sewing needle, the string material at the sewing position as well as the upper thread is drawn to the support member and then cut. Thus, after the string material and the upper thread are cut, only a slight amount of the string material is out of the guide, and only a slight amount of the upper thread remains at the tip of the sewing needle. In such a case, in performing sewing again after cutting the string material and the upper thread, it is necessary to pull out the slight amount of the string material out of the guide and the slight amount of the upper thread remaining at the tip of the sewing needle need by certain amounts. Particularly in multi-head sewing machines of a type which is provided with a plurality of machine heads, the string material and the upper thread must be pulled out in each machine head, which is very troublesome.